RAPID DEHYDRATION OF GRAPE BERRIES DAMPENS THE POST-RIPENING TRANSCRIPTOMIC PROGRAM AND THE METABOLITEPROFILE EVOLUTION

The postharvest dehydration of grape berries allows theaccumulation of sugars and other solutesand promotes the synthesis of aroma compounds unique to high-quality raisin wines such as thepassito wines made in Italy. These dynamic changes are dependent on environmental parameters such as temperature and relative humidity,as well asendogenous factors such as berry morphology and genotype, but the contribution of each variable isnot well understood.Here wecompared berries subjected to natural or accelerated dehydration, the latterdriven by forced airflow.We followed the evolution of transcript andmetaboliteprofiles and found that accelerated dehydration clearly dampened the natural transcriptomic and metabolomic programs of postharvest berries. We found that slow dehydration over a prolonged duration isnecessary to inducegene expression and metabolite accumulation associated with the final quality traits of dehydrated berries. The accumulation of key metabolites (particularly stilbenoids)during postharvest dehydration isinhibited by rapid dehydration conditions that shorten the berry life time. Transcriptomic changes occurring during post-harvest dehydration conducted in different environmental condition, were inspected by a microarray analysis performed on drying grape berries collected over the processes. At each time points, three biological replicates were collected.